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FAQ

Why do we prefer Kapitan to Helm?

Before developing Kapitan, we turned to Helm in an attempt to improve our old Jinja based templating system.

We quickly discovered that Helm did not fit well with our workflow, for the following reasons (which were true at the time of the evaluation):

Helm uses Go templates to define Kubernetes (yaml) manifests. We were already unsatisfied by using Jinja and we did not see a huge improvement from our previous system, the main reason being: YAML files are not suitable to be managed by text templating frameworks.

Helm does not have a solution for sharing values across charts, if not through subcharts. We wanted to be able to have one single place to define all values for all our templates. Sharing data between charts felt awkward and complicated.

Helm is component/chart based. We wanted to have something that would treat all our deployments as a whole.

We did not fancy the dependency on the tiller.

In short, we feel Helm is trying to be apt-get for Kubernetes charts, while we are trying to take you further than that.

Why do I need Kapitan?

With Kapitan, we worked to de-compose several problems that most of the other solutions are treating as one.

1) Kubernetes manifests: We like the jsonnet approach of using json as the working language. Jsonnet allows us to use inheritance and composition, and hide complexity at higher levels.

3) Hierarchical inventory: This is the feature that sets us apart from other solutions. We use the inventory (based on reclass) to define variables and properties that can be reused across different projects/deployments. This allows us to limit repetition, but also to define a nicer interface with developers (or CI tools) which will only need to understand YAML to operate changes.

4) Secrets: We manage most of our secrets with kapitan using the GPG, Google Cloud KMS and AWS KMS integrations. Keys can be setup per class, per target or shared so you can easily and flexibly manage access per environment. They can also be dynamically generated on compilation, if you don't feel like generating random passwords or RSA private keys, and they can be referenced in the inventory like any other variables. We have plans to support other providers such as Vault, in addition to GPG, Google Cloud KMS and AWS KMS.

5) Canned scripts: We treat scripts as text templates, so that we can craft pre-canned scripts for the specific target we are working on. This can be used for instance to define scripts that setup clusters, contexts or allow running kubectl with all the correct settings. Most other solutions require you to define contexts and call kubectl with the correct settings. We take care of that for you. Less ambiguity, fewer mistakes.

6) Documentation: We also use templates to create documentation for the targets we deploy. Documentation lived alongside everything else and it is treated as a first class citizen.
We feel most other solutions are pushing the limits of their capacity in order to provide for the above problems.
Helm treats everything as a text template, while jsonnet tries to do everything as json.
We believe that these approaches can be blended in a powerful new way, glued together by the inventory.